Someone typically of African descent dragging his long schlong down the back of your mom's throat, sometimes expanding it to the point of her being unrecognizable. You, as a son/daughter, are obviously watching this play out live in person, sometimes you join in, sometimes not.
Real white guy: Dude yesterday my mom gave that SLOPPY TOPPY GOOSE NECK to Tyrone. I had to join in because I am not a racist white nationalist who hates gays.
A sloppy toppy 5000 is the act of pulling off a play in Fortnite when you are at a significant disadvantage, for example a 1 v 4 or a 1v1 when you are on 30 health and the other guy just took a chug jug. If done successfully, a sloppy toppy 5000 must be followed by a forntie dance of some sort such as take the L or jubilation.
*you get revived*
*your whole team dies*
*it's a 1v4 and you're on 30 hp with a grey tac with 3 shells*
"Hold up lads, ya boi is about to pull off the sloppy toppy 500"
*pulls of sloppy toppy 5000"
proceeds to dance on the noobs